The drills come just one day after Russia accused coalition forces of harboring terrorists in the area and threatened to conduct operations and launch precision strikes around a key anti-ISIS coalition base in At Tanf.

The exercises, according to CENTCOM, are intended to send the Russians a message, specifically that the US and its partners do not need Russian, Syrian, or pro-regime assistance in eliminating terrorists in the region.

US troops are conducting a major live-fire exercise at At Tanf in Syria, US Central Command (CENTCOM) reported Friday, just one day after Russia accused the US-led coalition forces operating in the area of harboring terrorists and threatened to launch strikes in the deconfliction zone.

Russia informed the US on September 1 via the deconfliction line that Russian, Syrian, and other pro-regime forces intended to enter the At Tanf deconfliction zone to pursue ISIS terrorists, CENTCOM spokesman Lt. Col. Earl Brown told Business Insider on Friday, confirming an earlier report from CNN. The Russians then warned the US Thursday that they would carry out precision strikes in the area, a risky move that could easily spark a larger conflict.

More than 100 US Marines supported by air assets and artillery are conducting live-fire drills to send a "strong message" to Russia, Lucas Tomlinson at Fox News reported, citing US officials.

"Our forces will demonstrate the capability to deploy rapidly, assault a target with integrated air and ground forces, and conduct a rapid exfiltration anywhere in the OIR combined joint operations area," CENTCOM spokesman Capt. Bill Urban said in an official statement prior to the start of the exercises.

The combat exercises involving US troops, as well as Operation Inherent Resolve forces, are being held to send a clear message to Russia: The US does not need their help to take on terrorists in the area.

"The US does not require any assistance in our efforts to destroy ISIS in the At Tanf deconfliction zone and we advised the Russians to remain clear," Brown explained, adding, "Coalition partners are in the At Tanf deconfliction zone for the fight to destroy ISIS. Any claim that the US is harboring or assisting ISIS is grossly inaccurate.

"The Russians agreed to a 55-kilometer deconfliction zone around the At Tanf garrison to avoid accidental conflict between our forces, and to remain professionally engaged through deconfliction channels," he added, "We expect the Russians to abide by this agreement. There is no reason for Russian or pro-regime forces to violate the confines of that deconfliction zone."

Were Russia to violate the agreement, it could lead to a serious escalation in an already war-torn region.

"The United States does not seek to fight the Russians, the government of Syria or any groups that may be providing support to Syria in the Syrian civil war," Brown told BI, "However, the United States will not hesitate to use necessary and proportionate force to defend US, coalition or partner forces, as we have clearly demonstrated in past instances."

Earlier this year, roughly 40 US troops held off around 500 Russian mercenaries and pro-Syrian regime forces, reportedly killing hundreds.